Following the late fifteenth- and sixteenth-century cavalry revolution in Senegambia, the horse and slave trade became a major sector of the desert-edge political economy. Black African states imported horses from North Africa and the western Sahara in exchange for slaves. Over time, under conditions of increasing aridity, the zone of desert horse-breeding was pushed south, and through crossbreeding with the small disease-resistant indigenous horses of the savanna, new breeds were created. Although the savanna remained an epidemiologically hostile environment for the larger and more desirable horses bred in North Africa, in the high desert and along the desert fringe, Black African states continued to import horses in exchange for slaves into the period of French colonial rule.
The evidence assembled on the horse trade into northern Senegambia raises the difficult issue of the relative quantitative importance of the Atlantic and Saharan/North African slave trades and calls into question the assumption that the Atlantic slave trade was the larger of the two. Most available evidence concerns the Wolof kingdoms of Waalo and Kajoor. It suggests that the volume of slaves exported north into the desert from Waalo in the late seventeenth century was probably at least ten times as great as the volume of slaves exported into the Atlantic slave trade. For both Waalo and Kajoor, this ratio declined during the first half of the eighteenth century as slave exports into the Atlantic markets increased. The second half of the eighteenth century saw an increase in predatory raiding from the desert which produced an additional flow of north-bound slaves. For Waalo and Kajoor – and probably for the other Black African states of northern Senegambia – the flow of slaves north to Saharan and North African markets probably remained the larger of the two export volumes over the eighteenth century. This northward flow of slaves continued strong after the abolition of the Atlantic slave trade and was only shut down with the imposition of French colonial authority.